1. Field of Invention
The present invention relates to a vehicle and, more particularly, to a timing belt wound around timing gears of a vehicle and, more particularly, to a device for holding timing gears of a vehicle when a timing belt is disengaged from them.
2. Related Prior Art
A vehicle includes a timing belt wound around timing gears to drive cam shafts and a crank shaft to open and close valves of cylinders in a predetermined order. The timing belt is made of rubber that suffers fractures due to aging, excessive stress, erosion for example. The timing belt must be checked and replaced with a new one regularly to ensure normal operation of the vehicle.
To replace an old timing belt with a new timing belt, the relative angle between the timing gears must be retained to ensure precise timing of the opening and closing of the valves. If there is any error in the relative angle between the timing gears, the power of the engine will be jeopardized. If the error is minor, it can be corrected. If the error is serious, it could damage the engine and/or other elements related to the transmission of power.
Conventionally, a mark is made on the old timing belt and the relative angle between the timing gears is memorized before the old timing belt is removed from the timing gears. Later, the new timing belt is wound around the timing gears. Human memory is however not reliable, and the correct relative angle between the timing gears is not ensured. Hence, the new timing belt around the timing gears is always driven manually for several rounds before the engine is started, and this is an inconvenient practice.
The relative angle between the timing gears can be held with a holding device disclosed in U.S. Pat. No. 6,332,256. The holding device includes holding members 10, 11, 12 and 13 and connecting means 14. The connecting means 14 includes a connecting member 25 formed with two ends each pivotally connected to a relative one of the holding members 10 and 12. The holding members 11 and 13 are pivotally connected to the holding members 10 and 12, respectively. The holding member 10 includes a protuberance 19 that can be located between two adjacent ones of the teeth of a first timing gear. The holding member 11 includes a protuberance 20 that can be located between two other adjacent ones of the teeth of the first timing gear. The holding member 12 includes a protuberance 19 that can be located between two adjacent ones of the teeth of a second timing gear. The holding member 13 includes a protuberance 20 that can be located between two other adjacent ones of the teeth of the second timing gear.
Each of the holding members 10 and 12 includes a slot 21. A clamping screw is driven in each of the holding members 11 and 13 through the slot 21 defined in a related one of the holding members 10 and 12. Therefore, the relative position between the protuberances 19 and 20 is adjustable and the holding device can be used to hold the timing gears of various vehicles. It is however difficult to use the clamping screws to hold the relative position between the protuberances 19 and 20 since the clamping screws tend to slid along the slots 21.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.